Matplotlib: Adding Text and Annotation

Adding Text and Annotation

•  By adding text and annotations to the graph, we can make it more informative.

•  Let us discuss them one by one ‒

1) Adding Text

• We can add text to any desired location in the graph.

• The plt.text(x, y, "text") function adds text at a specific location.

Demo example

import matplotlib.pyplot as plt

x = [1, 2, 3, 4, 5]

y = [10, 15, 20, 25, 30]

plt.plot(x, y,marker='0')

# Add text

plt.text(3, 20, "Mid Point", fontsize=14, color='black')

plt.show()

Output

• In above program we have the text "Mid Point" is placed at (x=3, y=20). The fontsize=12 sets the text size.

2) Adding annotations

• The annotate() function adds an annotation with optional arrows pointing to specific points on the graph.

Demo example

import matplotlib.pyplot as plt

x = [1, 2, 3, 4, 5]

y = [10, 15, 20, 25, 30]

# Scatter plot

plt.scatter(x, y, color='green')

# Annotate the highest point

plt.annotate("Peak Point", xy=(5, 30), xytext=(6, 30),

     arrowprops=dict(arrowstyle="‒>"), fontsize=12)

# Annotate the lowest point

plt.annotate("Lowest Point", xy=(1, 10), xytext=(1.5, 4),

       arrowprops=dict(facecolor='blue', shrink=0.02))

plt.show()

Output

Code explanation: In above program,

1) plt.annotate("Peak Point", xy=(5, 30), xytext=(6, 30),

       arrowprops=dict(arrowstyle="‒>"), fontsize=12)

• This line annotates the highest point (5, 30) with the label "Peak Point".

• The annotate() function is used for this purpose.

• The xy parameter specifies the the coordinates of the point being annotated, ted, and xytext specifies the location of the annotation text.

• The arrowprops parameter defines the properties of the arrow and fontsize sets the font size of the annotation text.

2) plt.annotate("Lowest Point", xy=(1, 10), xytext=(1.5, 4),

arrowprops= dict(facecolor='blue', shrink=0.02))

• This line annotates the lowest point (1, 10) with the label "Lowest Point".

• Similar to the previous annotation, xy specifies the point being annotated and xytext specifies the location of the text.

• The arrowprops parameter defines the properties of the arrow, including facecolor which sets the arrow color to blue, and shrink which slightly shrinks the arrow from the text to the point.